Rats, birds, fish — even flies and worms — can stand in for people in laboratory testing. This allows scientists to safely evaluate harmful chemicals as well as to identify and test potential new drugs. But such tests will never be a foolproof gauge of effects in people.

Scientists used lasers to show that plants can “hear” insect pests. Those leafy plants then mount a chemical attack in response to the bug’s chewing sounds — but not toward harmless noises such as a gentle breeze or a bug’s mating call.